{"version":3,"file":"static-file-cache.js","names":[],"sources":["../../src/server/static-file-cache.ts"],"sourcesContent":["/**\n * Startup metadata cache for static file serving.\n *\n * Walks dist/client/ once at server boot, pre-computes response headers for\n * every file variant (original, brotli, gzip, zstd), and caches everything\n * in memory. The per-request hot path is just: Map.get() → string compare\n * (ETag) → writeHead(precomputed) → pipe.\n *\n * Modeled after sirv's production mode. Key insight from sirv: pre-compute\n * ALL response headers at startup — Content-Type, Content-Length, ETag,\n * Cache-Control, Content-Encoding, Vary — as reusable objects. The common\n * per-request path (no extraHeaders) does zero object allocation for headers.\n */\nimport fsp from \"node:fs/promises\";\nimport path from \"node:path\";\n\n/** Content-type lookup for static assets. Shared with prod-server.ts. */\nexport const CONTENT_TYPES: Record<string, string> = {\n  \".js\": \"application/javascript\",\n  \".mjs\": \"application/javascript\",\n  \".css\": \"text/css\",\n  \".html\": \"text/html\",\n  \".json\": \"application/json\",\n  \".png\": \"image/png\",\n  \".jpg\": \"image/jpeg\",\n  \".jpeg\": \"image/jpeg\",\n  \".gif\": \"image/gif\",\n  \".svg\": \"image/svg+xml\",\n  \".ico\": \"image/x-icon\",\n  \".woff\": \"font/woff\",\n  \".woff2\": \"font/woff2\",\n  \".ttf\": \"font/ttf\",\n  \".eot\": \"application/vnd.ms-fontobject\",\n  \".webp\": \"image/webp\",\n  \".avif\": \"image/avif\",\n  \".map\": \"application/json\",\n  \".rsc\": \"text/x-component\",\n};\n\n/**\n * Files below this size are buffered in memory at startup for zero-syscall\n * serving via res.end(buffer). Above this, files stream via createReadStream.\n * 64KB covers virtually all precompressed assets (a 200KB JS bundle compresses\n * to ~50KB with brotli q5).\n */\nconst BUFFER_THRESHOLD = 64 * 1024;\n\n/** A servable file variant with pre-computed response headers. */\ntype FileVariant = {\n  /** Absolute file path (used for streaming large files). */\n  path: string;\n  /** Uncompressed or encoded byte size for buffer-threshold decisions. */\n  size: number;\n  /** Pre-computed response headers. */\n  headers: Record<string, string>;\n  /** In-memory buffer for small files (below BUFFER_THRESHOLD). */\n  buffer?: Buffer;\n};\n\ntype StaticFileEntry = {\n  /** Weak ETag for conditional request matching. */\n  etag: string;\n  /** Pre-computed headers for 304 Not Modified response. */\n  notModifiedHeaders: Record<string, string>;\n  /** Original file variant (uncompressed). */\n  original: FileVariant;\n  /** Brotli precompressed variant, if .br file exists. */\n  br?: FileVariant;\n  /** Gzip precompressed variant, if .gz file exists. */\n  gz?: FileVariant;\n  /** Zstandard precompressed variant, if .zst file exists. */\n  zst?: FileVariant;\n};\n\n/**\n * In-memory cache of static file metadata, populated once at server startup.\n *\n * Usage:\n *   const cache = await StaticFileCache.create(clientDir);\n *   const entry = cache.lookup(\"/assets/app-abc123.js\");\n *   // entry.br?.headers, entry.original.headers, etc.\n */\nexport class StaticFileCache {\n  private readonly entries: Map<string, StaticFileEntry>;\n\n  private constructor(entries: Map<string, StaticFileEntry>) {\n    this.entries = entries;\n  }\n\n  /**\n   * Scan the client directory and build the cache.\n   *\n   * Gracefully handles non-existent directories (returns an empty cache).\n   */\n  static async create(clientDir: string): Promise<StaticFileCache> {\n    const entries = new Map<string, StaticFileEntry>();\n\n    // First pass: collect all regular files with their metadata\n    const allFiles = new Map<string, { fullPath: string; size: number; mtimeMs: number }>();\n\n    for await (const { relativePath, fullPath, stat } of walkFilesWithStats(clientDir)) {\n      allFiles.set(relativePath, { fullPath, size: stat.size, mtimeMs: stat.mtimeMs });\n    }\n\n    // Second pass: build cache entries with pre-computed headers per variant\n    for (const [relativePath, fileInfo] of allFiles) {\n      // Skip precompressed variants — they're linked to their originals\n      if (\n        relativePath.endsWith(\".br\") ||\n        relativePath.endsWith(\".gz\") ||\n        relativePath.endsWith(\".zst\")\n      )\n        continue;\n\n      // Skip .vite/ internal directory\n      if (relativePath.startsWith(\".vite/\") || relativePath === \".vite\") continue;\n\n      const ext = path.extname(relativePath);\n      const contentType = CONTENT_TYPES[ext] ?? \"application/octet-stream\";\n      const isHashed = relativePath.startsWith(\"assets/\");\n      const cacheControl = isHashed\n        ? \"public, max-age=31536000, immutable\"\n        : \"public, max-age=3600\";\n      const etag =\n        (isHashed && etagFromFilenameHash(relativePath, ext)) ||\n        `W/\"${fileInfo.size}-${Math.floor(fileInfo.mtimeMs / 1000)}\"`;\n\n      // Base headers shared by all variants (Content-Type, Cache-Control, ETag)\n      const baseHeaders = {\n        \"Content-Type\": contentType,\n        \"Cache-Control\": cacheControl,\n        ETag: etag,\n      };\n\n      // Pre-compute original variant headers\n      const original: FileVariant = {\n        path: fileInfo.fullPath,\n        size: fileInfo.size,\n        headers: { ...baseHeaders, \"Content-Length\": String(fileInfo.size) },\n      };\n\n      const entry: StaticFileEntry = {\n        etag,\n        notModifiedHeaders: { ETag: etag, \"Cache-Control\": cacheControl },\n        original,\n      };\n\n      // Pre-compute compressed variant headers (with Content-Encoding, Vary, correct Content-Length)\n      const brInfo = allFiles.get(relativePath + \".br\");\n      if (brInfo) {\n        entry.br = buildVariant(brInfo, baseHeaders, \"br\");\n      }\n\n      const gzInfo = allFiles.get(relativePath + \".gz\");\n      if (gzInfo) {\n        entry.gz = buildVariant(gzInfo, baseHeaders, \"gzip\");\n      }\n\n      const zstInfo = allFiles.get(relativePath + \".zst\");\n      if (zstInfo) {\n        entry.zst = buildVariant(zstInfo, baseHeaders, \"zstd\");\n      }\n\n      // When compressed variants exist, the original needs Vary too so\n      // shared caches don't serve uncompressed to compression-capable clients.\n      if (entry.br || entry.gz || entry.zst) {\n        original.headers[\"Vary\"] = \"Accept-Encoding\";\n        entry.notModifiedHeaders[\"Vary\"] = \"Accept-Encoding\";\n      }\n\n      // Register under the URL pathname (leading /)\n      // NOTE: aliases below share the same entry by reference, so all header\n      // mutations (e.g. Vary above) must happen before registration.\n      const pathname = \"/\" + relativePath;\n      entries.set(pathname, entry);\n\n      // Register HTML fallback aliases (same entry object — no duplication)\n      if (ext === \".html\") {\n        if (relativePath.endsWith(\"/index.html\")) {\n          const dirPath = \"/\" + relativePath.slice(0, -\"/index.html\".length);\n          if (dirPath !== \"/\") {\n            entries.set(dirPath, entry);\n          }\n        } else {\n          const withoutExt = \"/\" + relativePath.slice(0, -ext.length);\n          entries.set(withoutExt, entry);\n        }\n      }\n    }\n\n    // Third pass: buffer small files in memory for zero-syscall serving.\n    // For small compressed variants (e.g. a 50KB JS bundle → ~15KB brotli),\n    // res.end(buffer) is ~2x faster than createReadStream().pipe() because\n    // it skips fd open/close and stream plumbing overhead.\n    // Reads are chunked at 64 concurrent to avoid fd exhaustion on large projects.\n    // Deduplicate at the entry level first: HTML aliases share the same\n    // StaticFileEntry by reference, so entries.values() yields duplicates for\n    // paths like /about and /about.html. Deduping entries avoids iterating\n    // their variants multiple times on sites with many HTML pages.\n    const toBuffer: FileVariant[] = [];\n    const seenEntries = new Set<StaticFileEntry>();\n    for (const entry of entries.values()) {\n      if (seenEntries.has(entry)) continue;\n      seenEntries.add(entry);\n      for (const variant of [entry.original, entry.br, entry.gz, entry.zst]) {\n        if (!variant || variant.size > BUFFER_THRESHOLD) continue;\n        toBuffer.push(variant);\n      }\n    }\n    for (let i = 0; i < toBuffer.length; i += 64) {\n      await Promise.all(\n        toBuffer.slice(i, i + 64).map(async (v) => {\n          v.buffer = await fsp.readFile(v.path);\n        }),\n      );\n    }\n\n    return new StaticFileCache(entries);\n  }\n\n  /**\n   * Look up cached metadata for a URL pathname.\n   *\n   * Returns undefined if the file is not in the cache. 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